A chipper apparatus or “chipper” is used in the field of lumber pulp production to process logs and to cut them or “chip” them into smaller pieces. In so-called “disc” chippers, a large rotary disc retains a series of radially disposed cutting knives on a facing surface of the disc. This disc can be adjusted in relation to a stationary cutting knife, commonly referred to by those of ordinary skill in the field as a “bedknife” or “anvil”.
The large rotary disc is usually mounted for rotation onto a shaft that is driven by either an electric or diesel motor that may be coupled to a gear box. The chipper disc and shaft are held by two (2) large bearings. These bearings are affixed to the driven shaft, but are allowed to move axially in their respective housings. An exemplary setup of this type is shown in FIG. 3. Adjustment of the rotary disc permits the proper distance to be set from the radially disposed cutting knives in relation to the stationary bedknife.
In addition to an initial adjustment that would be required for a chipper apparatus, later reset adjustments of the disc relative to the bedknife in terms of clearance may be required. For example, such adjustments may be required when a bedknife or bedknife liners have been changed, when knife segments of the rotary disc have been changed, when new cutting knives having different widths than knives just removed from the rotary disc are employed, or when the axial position of the disc has been adjusted for any reason, such as during a maintenance procedure.
Referring to FIGS. 1-3, and in order to provide this type of adjustment for known chipping apparatus, it has previously been necessary for two persons to utilize a large open end wrench 130 and sledgehammer 140 to first loosen a clamping or locking nut 104 in order to loosen the locking nut from an adjusting nut 120.
After the locking nut 104 has been loosened, it is still necessary for at least one operator to use a large open end wrench 130 and sledgehammer 140 in order to selectively turn the adjusting nut 120 in order to axially adjust a chipper thrust screw away from the bedknife in order to increase clearance between the rotary cutting knives of the cutting disc and the bedknife or alternatively, to pull the chipper thrust screw and the rotary disc toward the stationary bedknife.
In brief, movement is facilitated in the chipper apparatus shown in FIGS. 1-3 using a thrust bearing assembly in which the adjusting nut 120 and the locking nut 104 are each attached to a coaxial displaceable shaft whose output is connected to a thrust bearing cartridge assembly, which is axially movable, the cartridge being attached to the shaft of the chipper disc.
Following the above known adjustment procedure, it is necessary to lock the above assembly in place in the desired position prior to chipper operation. To accomplish the task of setting the cutting disc into position and locking it there, the adjusting nut 120 must be rotated in one direction (e.g., clockwise) in order to shift the large rotary disc toward the stationary bedknife. The adjusting nut 120 must then be rotated in the opposite direction in order to remove slack from the assembly and the locking nut 104 must be tightened until the locking nut firmly engages the adjusting nut 120. Again and as shown in FIG. 1, at least two persons are required wherein one person must support the large wrench 130 onto the adjusting nut 120, while the other person uses a separate wrench 130 and sledgehammer 140 in order to tighten the locking nut 104.
Other assemblies for adjusting the clearance position of the rotary cutting disc of chipper apparatus are known, such as described, for example, in U.S. Pat. No. 5,727,611. These assemblies are relatively complex and also require separate and various loosening and tightening procedures in order to effect adjustment.
There is a need to simplify and improve the adjustment procedure such that a single person can perform this procedure, as needed, and also such that adjustments can be made reliably and expediently.